Tuning indicator tube



Jan. 21, 1964 E. s. ELVERS 3,119,039

TUNING INDICATOR TUBE Filed July 7. 1960 FIG.3

INVENTOR ERNST 6. ELVERS BY M 16 l -AK' AGENT United States Patent 3,119,039 TUNING INDICATOR TUBE Ernst Giinter Elvers, Hamburg, Germany, assignor to North American Philips Company, Inc, New York,

NY, a corporation of Delaware Filed July 7, 1960, 'Ser. No. 41,359 Claims priority, application Germany July 15, 1959 4 Claims. (Cl. 313-4075) This invention relates to a tuning indicator tube to indicate several measured values. Such tubes generally have a separate electrode system, in which the electron beams emitted from a cathode are deflected by deflector electrodes and impinge on a fluorescent screen. In a known embodiment of tuning indicator tubes, the fluorescent screen has the shape of a strip. In accordance with the voltage applied to the deflector electrodes, which voltage is the same for all the deflector electrodes, the strip of the fluorescent screen is illuminated from its ends by the impinging electrons. Between the illuminated strip zones there is a sharply defined dark zone which, in case of larger driving action, becomes narrower and may even disappear. The extension of the bright zones occurs invariably simultaneously and equally strongly from the two ends of the strip. This form of indication is very clearly observable.

The deflector electrodes of these tubes are shaped as rods which are arranged one behind the other in the direction of the electron beam; they render the indication of only one measured value possible.

The visible indication of only one measured value, however, is not always sufficient in the case of electric telecommunication devices. In these apparatus it is often necessary to indicate at least two measured values.

This is the case, for example, if both the field strength of an amplitude-modulated transmitter and the detuning direction of a frequency-modulated transmitter have to be indicated. In addition, this indication would be suitable for the indication of the extent of driving of the two channels in stereo-recording and -reproduction.

It is known to provide, for this purpose, in the envelope of a tuning indicator tube two electrode systems operating independently from each other, the electron beams of which tube are directed beside each other on a fluorescent strip or on two fluorescent strips lying beside each other. However, this construction is uneconomic, it corresponding actually to the use of two tubes. In addition, the transitions from the illuminated strip zones to the dark zones extend at an angle towards each other or even show curvatures. The picture reproduced by this tube therefore is disturbed.

It is known in addition to combine the two systems, two plate-shaped deflector electrodes being provided, at each of which a different potential is set up. Each of the plates consequently causes a different deflection of the electron beams in its proximity. The plates are provided so remote from one another that the electron beams can pass between them in case of maximal dispersion of the beams. However, this arrangement causes an illuminated Zone which widens from the center of the illuminated strip towards both sides. The variations in the size of the illuminated zone at the two sides of the middle line of the light strip depend on the potential to which the deflector plates are connected. It is true, this arrangement is actually simpler than that which employs two separate systems, but the picture reproduced on the fluorescent screen gives little satisfaction since the size variations of the illuminated zone do not contrast clearly enough against the dark zones at the strip edges, as a result of which they are observed only indistinctly.

Owing to the defects in the indication picture, the known indicator tubes with double indication have so 3,119,039 Patented Jan. 21, 1964 'ice far found no acceptance. The object of the invention is to provide a tube of simple structure giving a conspicuous and at the same time quiet indication.

In a tuning indicator tube according to the invention for the indication of several measured values, deflector electrodes, separated from one another in a conductive manner with an insulation layer, therebetween, are pro vided in parallel and close beside one another in the electron path between an emission system and the fluorescent screen and are combined into one set.

Since the deflector electrodes in this construction are arranged close to one another and are both of different potential, an electric field is set up between these plates which may cause charging of the insulation layer between the electrodes preferably consisting of mica. Disturbances of the deflector fields by this field may be suppressed in the simplest manner by causing the deflector electrodes to project over the insulation layer. The central plane of the set of electrodes consisting of the deflector electrodes and the insulation layer is provided in a plane extending at right anglesto the fluorescent screen and-through the center of the cathode. By means of the electrode arrangement according to the invention, the indication is effected, as is the case with the known tuning indicator tubes having a strip-shaped fluorescent screen and only one deflector electrode system, by reducing the dark zone between the strip ends. In contrast to the known tube, however, the illuminated zones widen independently of one another, since the illuminated zone extending from the one strip end is controlled by the one deflector electrode and the illuminated zone extending from the other strip end is controlled by the other deflector electrode. The bright-dark boundaries invariably extend at right angles to the strip axis. By means of this tube, the variations of the measured values are clearly observable without having a disquieting effect on the viewer.

In order that the invention may be readily carried into eflect, it will now be described in greater detail, by way of example, with reference to the embodiment shown in the drawing in which FIG. 1 is a diagrammatic sectional view through the electrode system according to the invention,

FIG. 2 is the elevation A as shown in FIG. 1 of the fluorescent screen,

FIG. 3 is a sectional View of the arrangement of the deflector electrodes through the line B-C shown in FIG. 1.

The cathode 1 shown in FIG. 1 of a tuning indicator tube is surrounded by a reflection grid 2, the support rods '3 of which are both provided on one side of the cathode. On the opposite side of the cathode and at comparatively large distance from the cathode 1 a light screen 6 is provided on the tube wall 5, on which electron beams 7, 8 emerging from the cathode 1 and the grid 2 impinge. At right angles to the fluorescent screen 6 and between this screen and the emission system comprising the cathode 1 and the grid 2, deflector plates 9, 10 are provided closely engaging one another at equal distance from the emission system with the interposition of an insulation layer 11, for example of mica. Both the cathode 1 and the grid 2, and also the anode 4 and the deflector plates 9 and 10 are in known manner provided with and held by slices of insulation material 12. The deflection voltages supplied to the deflector plates may be produced either in a separate double triode or in two 'triodes likewise provided in the envelope of the tube.

In the case of low potential of the deflector plates 9 and 10, the electron beams 7 and 8 first impinge in two beams on the ends of the fluorescent screen 6 constituted by the strip (FIG. 2). lit the potential at the one deflector plate 9 is increased. the electron beam 7, which is opposite to this deflector plate 9, is dispersed in the direction of the plate 9. The electron beam 8 opposite to the other plate 19 is only slightly influenced by the potential variation. Only if the potential of the other plate 10 is changed, the electron beam 8 also situated opposite to this plate experiences a change. Both beams 7 and 8 are consequently controlled independently from one another. This independent control is noticeable on the fluorescent screen 6 because the illuminated zones 14 starting at the strip ends cover different distances towards the center of the strip (FIG. 2).

Each of the deflector plates 9, 15 of the particularly effective arrangement of the deflector plates as shown in FIG. 3, encloses a side face 16 of the insulation layer 11 between the plates 9 and It). This is reached because the the deflector plates 9 and It) provided in the slices of insulation material 12 project, with tags 15, over the sides 16 of the insulation layer 11. At their ends, the tags 15 are bent back and embrace, with a short projection 17, the side of the insulation layer to which the other deflector plate is provided. So the insulation layer 11 is firmly clamped and cannot perform any independent vibration. The tags 15 are connected to voltage supply conductors not shown.

What is claimed is:

1. An electron discharge device for indicating several measured values comprising an evacuated envelope, a

cathode within said envelope, a grid electrode spaced from said cathode, a target electrode spaced from the cathode, an anode electrode, and a pair of deflector electrodes positioned between the grid electrode and the target electrode perpendicular to the path of an electron beam generated by die cathode, said deflector electrodes being positioned in parallel to and in close adjacency to one another and being separated from one another by a layer of insulation therehetween whereby no electrons can pass between said deflector electrodes.

2. An electron discharge device as claimed in claim 1 in which each of the two deflector electrodes are connected to a source of different potential.

3. A tuning indicator tube as claimed in claim 1 in which the deflector plates project beyond the insulating layer and are bent over one side of said layer.

4. A tuning indicator tube as claimed in claim 1, in which the central plane of the set of electrodes comprising the deflector electrodes and the insulating layer is located in a plane extending at right angles to the fluorescent screen and through the center of the cathode.

References Cited in the file of this patent UNITED STATES PATENTS 2,829,294 Bitter et al Apr. 1, 1958 

1. AN ELECTRON DISCHARGE DEVICE FOR INDICATING SEVERAL MEASURED VALUES COMPRISING AN EVACUATED ENVELOPE, A CATHODE WITHIN SAID ENVELOPE, A GRID ELECTRODE SPACED FROM SAID CATHODE, A TARGET ELECTRODE SPACED FROM THE CATHODE, AN ANODE ELECTRODE, AND A PAIR OF DEFLECTOR ELECTRODES POSITIONED BETWEEN THE GRID ELECTRODE AND THE TARGET ELECTRODE PERPENDICULAR TO THE PATH OF AN ELECTRON BEAM GENERATED BY THE CATHODE, SAID DEFLECTOR ELECTRODES BEING POSITIONED IN PARALLEL TO AND IN CLOSE ADJACENCY TO ONE ANOTHER AND BEING SEPARATED FROM ONE ANOTHER BY A LAYER OF INSULATION THEREBETWEEN WHEREBY NO ELECTRONS CAN PASS BETWEEN SAID DEFLECTOR ELECTRODES. 